We report a study on the spectroscopy and the photochemistry of the allyl radical, C3H5, in the vacuum ultraviolet energy range using synchrotron radiation as the light source and a flash pyrolysis source to generate the radical. Mass spectra recorded over a wide energy range show the appearance of C3H3+ as a fragment in the dissociative photoionization of allyl above 10 eV. The threshold photoelectron spectrum of the allyl radical shows a progression of around 52 meV, corresponding to the CCC bending vibration. (C) 2003 American Institute of Physics.